1. Field of the Invention
The present invention relates generally to treatment of pathological conditions of the eye, and in particular to the use of lipid complexes of therapeutically active agents in treating such conditions.
2. Background Information
Direct delivery of drugs to the posterior segment of the eye by intravitreal injection of conventional nucleoside drugs, water soluble small and medium sized molecules, or intravitreal drug-containing implants has been used to treat chronic vitroretinal diseases. Compared to systemic drug administration for vitroretinal diseases, local intravitreal drug administration bypasses the blood-ocular barriers and provides a higher concentration of drug to the ocular tissue, while avoiding many of the side effects associated with systemic therapy.
Local intravitreal administration of slow-release drugs is especially desirable since frequent intravitreal administration (e.g., by injection) can cause retinal detachment and endophthalmitis. Indeed, attempts have been made to administer slow-release drugs using ocular implants. However, surgical placement and replacement of intravitreal implants can cause significant adverse effects, such as vitreous hemorrhage, retinal detachment, and infection. Intravitreal injection of a slow-release drug would be less invasive than surgery and could be reasonably repeated if the interval between injections is several weeks or longer.
To date, most intravitreally injected compounds have a short vitreous half life, which necessitates frequent injections to realize a therapeutic benefit. Liposome encapsulation of therapeutic compounds has been investigated in attempts to extend drug vitreous half life. However, liposomes may significantly decrease vitreous clarity and hence impair visual function.
Accordingly, a need exists for improved methods for delivering therapeutically active agents to the structures of the eye.